Device for supplying spray units for die casting machines with a fluid containing water and additives

ABSTRACT

The subject matter of the invention is a device for supplying spray units for die casting machines each with a fluid containing water and additives for cooling, cleansing and lubricating purposes. The device contains at least one central tank (26,28) storing water comprising additives, whose concentration has been adjusted to a maximum. Said maximum value depends on casting materials, molds (18,20) and die casting methods which are carried out on the die casting machines (10,12). In another central tank (44) water is stored. The tanks (26,28,44) are connected to mixing valves (38,40) provided at each die casting machine (10,12). A pump is connected between the outlet of each mixing valve and the inlet of a respective spray unit at a die casting machine.

BACKGROUND OF THE INVENTION

The invention relates to a device for supplying spray units for diecasting machines with a fluid containing water and additives forcooling, cleansing and/or lubricating purposes.

During die casting processes the opened mold's interior is wetted with afluid containing dissolved, suspended or emulsified additives prior tocasting. The fluid is used for separating, cooling and/or lubricating.The composition of the fluid is contingent upon the material and theshape of the castings, above all upon their wall thicknesses as well asupon the conditions for a rapid and simple removal from the mold. Thefluid is sprayed by spray units onto the walls of the mold. It is priorart to connect a spray unit arranged at a die casting machine with atank from which the fluid is delivered by means of compressed air to thedies of the spray unit (Praxis der Druckgiessfertigung von E. Brunhuber,1980, Fachverlag Schiele & Schon GmbH, on page 128).

Frequently, for diverse molds fluids having differing compositions andspray units adjusted to the respective mold are required. If at changingthe mold the fluid supply in the tank is not exhausted, the tank must beemptied and filled with a mixture harmonized with the other mold.Moreover, it may also happen that the tank's capacity does not sufficefor a major series of the same mold. Then, the die casting proceduremust be interrupted at exhaustion of the fluid supply during automaticoperation.

SUMMARY OF THE INVENTION

It is the object of the invention to create a device suited forautomatic operation for supplying one or several spray units for diecasting machines with each a fluid containing water and additives forcooling, cleansing and/or lubricating purposes.

According to the invention the above problem is solved by utilizing adevice for supplying a plurality of spray units, each for a die castingmachine, which comprises at least one first central tank for storingwater containing additives of a concentration being the maximumnecessary of the particular materials, molds and methods used, a furthercentral tank for storing water, a mixing valve having a first inletconnected to the first central tank and a second inlet connected to thefurther central tank, an outlet, and means for adjusting the proportionof liquid from the first and further central tanks delivered through theoutlet, and a pump for each spray unit having an inlet connected to theoutlet of a respective mixing valve, and an outlet connected to a sprayunit. The device as described makes an adjustment of the desired mixingratio by the mixing valve at the respective die casting machinepossible. Then, only the amount of fluid especially tailored to therespective mold is produced according to the necessity of the individualspraying procedure. At changing the molds nothing but the adjustment ofthe mixing valve must be altered if a new mixing ratio is required. Suchadjustment takes only short time. The process of production is,therefore, no longer affected by the time-consuming re-filling orexchanging of the fluid for the spraying step. By the device describedherein better use may be made of the die casting machines as there areless setting periods. It is the principle of present invention to storefluids having the highest concentration necessary and for making thedilution with water required for each casting step prior to spraying.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A preferred example of embodiment provides a number of central tankscorresponding to the type of casting materials to be treated in the diecasting machines, in which fluids each of water and additives are storedin the highest concentration required for the respective castingmaterial with a corresponding mold, the central tanks being coupledthrough reversing valves to a piping system to which the mixing valvesare connected. At a change of the type of die casting material to beprocessed, e.g. when changing from aluminum over to zinc die casting, onone or several of the die casting machines centrally supplied with sprayfluid the change-over to the suited spray fluid is brought about byopening the valve between the collecting pipe and the central tankprovided for the respective material as well as by bringing the mixingvalve adjustment into line with the material and the mold used. Thechange of the spray fluid is rapid and simple.

Preferredly, the central tanks are arranged higher than then die castingmachines. It is, thus, under the action of gravity that the fluids fromthe tanks reach the mixing valves. This is why expensive andenergy-consuming conveying means are rendered superfluous.

It is expedient to connect to the outlet of each mixing valve a pumpwhich feeds the spray unit for the die casting machine. By the aid of apump the amount of fluid to be sprayed can be adjusted exactly to therespective need. This results in an economic consumption of spray fluid.

Another preferred embodiment is to form the pump as a plunger pump,whose cylinder either is vertically disposed or may take any otherposition whatsoever, when it is guaranteed that gravity plays itsnecessary part through the media. In case of said example of embodimentfor the supplying and mixing of the respective fluids up to the fillingof the cylinder's interior with the mixture no pump is necessary. Saidprocedures are carried out under the action of gravity, and for thisreason the said device operates particularly economically.

Preferably, the plunger of the respective plunger pump shows two spaceddisks, one of which faces the cylinder volume designed to receive thefluid and the other of which faces the cylinder volume attackable bypressure gas, by which the interspace defined by said two disks can beconnected via a check valve at relief of the excess pressure. With saiddevice fluid penetrating the interspace while the the cylinder volumefilled with fluid is being pumped down, may enter into the cylindervolume no longer under gas pressure after termination of the pumpingstep and escape therefrom. By the plunger composed of two disks theproblem of sealing against the fluid and against the pressure gas issolved in a simple way.

The cylinder volume attackable by pressure gas is most suitably apt tobe connected by a reversing valve to the source of compressed airprovided for the spray unit. To actuate the pump and the spray unit onemay use the same source of compressed air.

At an advantageous embodiment a check valve is arranged at the outlet ofthe cylinder volume attackable by fluid. The pump may be positioned at asuitable place below the spray unit. The check valve prevents that fluidflows back from the spray unit to the pump resp. that the spray unitgives off drops.

An advantageous embodiment of a mixing valve resides in that acylindrical body rotatably mounted in a casing has a concentric cavityopen towards one side and a radial slot which may be turned around asagainst two inlet openings in a casing wall for the fluid and for waterby countercurrent change of the inlet cross-sections, check valves beingintroduced before the inlet openings. At pumping down the cylinder thecheck valves prevent a flow-back of the fluid contained in the cylinderinto the central tanks. The cylindrical body may be provided with alever whose one end is formed as an indicating tip for a scale. The saidembodiment renders the manual adjustment of the mixing ratio possible.But the cylindrical body may also be provided with a motor drive and theangle position of the cylindrical body may be detected by aposition-indicating means, as well. A potentiometer giving an analogindication or a coding disk by which the position may be detecteddigitally are suitable position-indicating means. A geared motor can beused as a motor drive.

Preferably, the cylinder of the pumps is composed of two disks and acylindrical jacket arranged between the disks. Said embodiment can beproduced economically. A relatively thin-walled cylindrical jacketsuffices. To limit the travel of plunger stops may be provided in thecylinder. By an adjustment of the stops the suction volume of thecylinder and, hence, the amount of the fluid to be sprayed can bepregiven.

Other particulars, features and advantages of the invention areresultant from the following description of an illustrated example ofembodiment.

FIG. 1 shows a schematic view of a device for supplying spray units fordie casting machines;

FIG. 2 is a perspective view of a mixing valve and a pump of the deviceshown in FIG. 1;

FIG. 3 is a longitudinal section through the device illustrated by FIG.2; FIG. 4 is a cross-section along lines III--III of the device shown inFIG. 3.

Die casting machines 10, 12, two of which are shown in FIG. 1, each havespray units 14,16 by which the surfaces of molds 18,20 each consistingof a stationary and a movable half are sprayed on. The two halves ofmolds 18,20 are not designated any closer. The two die casting machineseach reveal a machine bed and posts arranged thereon. The stationarymold halves and hydraulic elements are fixed on said posts. Thehydraulic elements move a sliding carriage and the movable mold halfaffixed thereto during the manufacture of the castings. The machine bed,the posts and the hydraulic elements are designated more particularly inFIG. 1.

The spray units 14,16 each spray a fluid for cooling, cleansing and/orlubricating purposes onto the mold surfaces. Spray units 14,16 areprovided with spray nozzles adjustable as regards direction - notdesignated more closely and are mounted slidably and pivotally bothhorizontally and vertically on carriers 22,24. Carriers 22,24 each aredisposed on one of the machine posts. The fluids to be sprayed consistof water containing additives which may be graphite, pigments or thelike in conjunction with special active ingredients and carriers. Inmany cases emulsive pigment-free additives are used.

For different molds 18,20 and different casting materials fluids ofdifferent compositions are frequently needed. Spray units 14,16 oftenmust be exchanged or adjusted anew under adaptation to another mold, aswell.

To supply spray units 14,16 with fluids whose compositions are broughtinto line with the respective conditions of the production methodapplied on the die casting machine 10,12 a device having at least onetank 26 central as against spray units 14,16 is used. Tank 26 containswater and additives in the highest concentration necessary.Concentration is adjusted to that mold and that casting material whichneed the highest proportion of additives for making perfect castings.The additives may be diluted with water at e.g. a ratio of 1:50 or 1:80.If different additives are needed for different casting materials, e.g.aluminum or zinc die-casting, further central tanks containing fluids inwhich the corresponding additives are dissolved in the highestconcentration necessary must be provided for. FIG. 1 shows only oneadditional central tank. If need be, several central tanks can beprovided for.

On their outlet side the central tanks 26,28 are connected throughpipings 30,32 with a reversing valve 34, whose outlet is coupled to acentral piping system 36 which comprises departures--not designated anycloser--extending to die casting machines 10,12 and further die castingmachines not shown. At the die casting machines 10,12 and the other diecasting machines there are mixing valves 38,40, each of which isconnected by one inlet to the piping system 36. Through a second inleteach the mixing valves 38,40 are connected to a piping system 42 whichis fed by central tank 44 containing water. Central tanks 26,28,44 areat one level above die casting machines 10,12. This is why water fromtank 4 4 and the fluid selected each thrgugh reversing valve 34 reachthe mixing valves 38,40 at the die casting machines 10,12 under theaction of gravity and under substantially the same pressure. Theconcentration of the additives in water as necessitated for therespective process of production is produced by admixing water from tank44 in the adjustable mixing valves 38,40.

To mixing valves 38,40 pumps 46,48 each are subsequented which arearranged e.g. at the level of the machine bed of the respective diecasting machine 10,12. On the outlet side pumps 46,48 each are coupledto spray units 14,16 via pipings 50,52. Pipings 30,32, reversing valve34, piping system 36, mixing values 38,40, piping system 42, tank 44 andpumps 46,48 and tanks 26,28 are part of the device by which the diecasting machines 10,12 are supplied centrally and automatically eachwith a fluid containing water and additives in a concentrationadjustable at the mixing valves 38,40.

To control the water level in tank 44 said tank 44 is provided with ameans 54. If the water level goes under a defined level, this will bedetected by a level sensor which is part of means 54. Said level sensoropens a tap within a pipe fed by the water piping system to tank 44 tillthe desired level is reached.

Tanks 26 and 28 have also level sensors 56 which control dosing means58. Said dosing means 58 produce the fluids determined for tanks 26,28from the additives and the water fed.

Pumps 46,48, one of which is illustrated as a perspective view in FIG. 2and IN CROSS SECTION IN FIG. 3, each have a cylindrical jacket 60 whichis held between an upper disk 62 and a lower disk 64 by using sealingsnot designated more detailedly. Disks 62,64 are of rectangular shape.Disks 62,64 are connected by stay bolts 66 at the four angles. Pumps46,48 stand with their cylinders at die casting machines 12,10. To theupper disk 62 each the mixing valve 38 resp. 40 is fixed.

Mixing valves 38,40 are provided with each a connecting member 68 forthe fluid supplied by tanks 26 or 28 and with a connecting member 70 forwater supplied from tank 44. In a cylindrical casing 72 or the mixingvalves 38,40 a bearing 74 in which a cylindrical body 76 is rotatablymounted is fixed. Cylindrical body 76 consists of two section 78,80having differing diameters. Section 78 having the larger diameter showsa cylindrical recess 82 which is open towards the side of mixing valve38 resp. 40 facing pump 46,48. In section 78 there is slot 84 extendingover the entire half of the circular ring of the wall surrounding recess82. At the level of slot 84 on diametrically opposite positions ofcasing 72 and bearing 74 there are each cylindrical recesses 86,88 forthe inlet of water and fluid. Recesses 86, 88 are each connected withthe cavities of connecting members 68,70--the cavities not beingdesignated any closer--which are screwed into casing 72. Dependent uponthe adjustment of angle of the slot 84 as against recesses 86,88 themixing ratio of the fluid arriving through connecting member 68 and thewater arriving at connecting member 70 may be modified. Between oneposition each of slot 84, in which either the recess 86 resp. 88 iscompletely closed or the the recess 88 resp. 86 is open towards recess82, and other positions of slot 84 differing cross-sections of aperturewhich determine the respective mixing ratio are achieved.

The front sides of connecting members 68,70 which lie within theinterior of casing 72 and are not designated any closer are formed asvalve seats for valve disks 90,92 which are spring-loaded against thevalve seats. Valve disks 90,92, the valve seats and the springs notdesignated with more detail, whose ends are supported by valve disks90,92 and spring rings 94 in recesses 86,88 are check valves.

On its side averted from pump 46 resp. 48 the casing 72 is closed by aplate-shaped cover 96 having an aperture--not designated anycloser--through which section 80 of body 76 projects outwardly. In abore extending approximately radially in section 80 a lever 98 isinserted and then clamped with a screw. Lever 98 projects from bothsides of section 80. One end 100 of lever 98 is knobbed, while the otherend of lever 98 is formed as a pointer 102 which is rotatable abovescale 104 from which the mixing ratio may be taken. Through lever 98 theposition of angle of slot 84 may be brought manually into harmony with adesired mixing ratio.

In place of lever 98 or in addition to lever 98 the shaft of motor 106,e.g. of a geared motor, may be connected to section 80. Motor 106 isdash-dotted above the front side of section 80 in FIG. 2. By motor 106slot 84 may be adjusted by distant control to the desired angleposition. To report the angle position of slot 84 e.g. a rotary or anglepotentiometer 81 which at the tap gives a potential dependent on theangle position and being detected by a central control may be used. Bythe aid of the rotary potentiometer, whose output signal is centrallydetected, and motor 106 which is centrally supplied with controlpotential an automatic adjustment of the mixing ratio to valuespre-given by e.g. a programmable control device can be achieved.

Casing 72 of mixing valve 38 resp. 40 is fixed to disk 62 of pump 46resp. 48 such that the recess 82 is in alignment with an inlet 108 indisk 62. Inlet 108 opens out into cylinder volume 110 within thecylinder formed by disks 62, 64 and jacket 60, wherein plunger 114 ismovably arranged. Plunger 114 contains two spaced plunger disks 116,118connected by centric tappet 120. Under disk 118 there is cylinder volume122 apt to be connected by bore 124 with a source of compressed air 126which also feeds spray units 14,16. In plunger disk 118 there is checkvalve 128 by which the interspace 130 confined by plunger disks 116,118can be connected with cylinder volume 122, if there is no excesspressure in cylinder volume 122.

The cylinder volume has an outlet opening 132 arranged in disk 62, aconnecting member 134 being screwed into it. At the end facing thecylinder volume 110 the outlet opening 132 has an annular projection 136against which cover 138 is sealingly pressed under spring-load. Spring140 is supported by a shoulder in connecting member 134 and cover 138.Cover 138 forms a check valve with projection 136 and spring 140.

The fluid provided with the additives in the highest concentrationnecessary comes from tanks 26 and 28 via pipes 30,32 to reversing valve34 selecting tank 26 or 28. The adjustment of reversing valve 34determines the connection of tank 26 or 28 to piping system 36 mostsuitably having an outlet tap by which prior to a switch-over to anothertank the fluid still contained in the piping system can be removed.Through piping system 36 fluid reaches connecting members 68 of mixingvalves 38,40. From tank 44 water enters via piping system 42 intoconnecting members 70 of the mixing valves 38,40. By the action ofgravity of the fluid resp. of the water valve disks 90,92 are openedand, thus, fluid and water reach body 76 each via recesses 86 and 88.Through the free cross-section--dependent on the position of angle ofslot 84--at the orifice of recess 86 resp. 88 each fluid and water enterinto slot 84. Fluid and water mix in slot 84 and recess 82. Via inlet108 the mixture comes into cylinder volume 110 filling with fluidmixture whose mixing ratio depends on the position of angle of slot 84.Dependent upon the production program for which the die casting machines10,12 are equipped the positions of angle of slots 84 differ in mixingvalves 38,40.

Between source 126 of compressed air and bores 124 there are reversingvalves 142,144 each, which may be operated manually or by some control.In the idle position of plunger 114 atmospheric pressure is applied tocylinder volume 122 through reversing valves 142,144. Here, plunger 114lies close to stops 146 which are formed as screws and which are screwedinto disk 64 and limit the travel of stroke of plunger 114. Via thetravel of stroke the maximum cylinder volume 110 disposable for thefluid mixture is determined by the stops 146 and, thus, the fluid amountprovided for spraying.

If cylinder volume 122 is under atmospheric pressure, the fluid havingpenetrated interspace 130 between plunger disk 116 and jacket 60 mayreach cylinder volume 122 through check valve 128 and escape into theatmosphere.

If fluid is to be sprayed onto molds 18,20 the cylinder volumes 122 areconnected each by reversing valves 142,144 to the source 126 ofcompressed air. At the same time spray units 14,16 are supplied bysource of compressed air 126 with compressed air. At the compressedair's impinging on plunger 114 it is moved upwardly, a working pressureof e.g. 7 bar being generated in cylinder volume 110. The check valvesin mixing valves 38,40 close under the pressure in the working spacesuch that no fluid is pumped back from the cylinder volume 110 intotanks 26,28,44. The fluid each leaves cylinder volume 110 via outletopening 132 and comes into pipings 50 resp. 52 extending to spray units14,16.

When plunger 114 has displaced the fluid from the cylinder 112, anatmospheric pressure is applied to the cylinder volume 122 by reversingvalves 142,144, which may be electromagnetically operable controlvalves, as well. By the pressure discharge of plunger 114 the checkvalve constituted of elements 136,138,140 closes, the return of fluidfrom the spray units 14,16 and the pipings 50,52 being prevented. Thischeck valve is adjusted so as to close already at drop of the pressureto 2 bar in the cylinder volume 110. At the same time, this preventsmost advantageously an after-dropping at the spray units 14,16, and thusno undesired influence on the surface of the open mold 18,20 by droppingmay make itself felt. Pumps 46,48 are arranged at a level lower thanthat of spray units 14,16.

Plunger 114 which may be formed from one piece has a certain axialexpansion so that the exertion of low pressure is sufficient to actuateplunger 114. When fluid comes into interspace 130, it is removed throughthe check valve 128. This guarantees a uniform faultless mode of workingof plunger 114. As it is worked at low pressure in cylinder 112, thejacket 60 may have a thin wall.

Owing to the level control the central tanks 26,28,44 may be given smallvolumes. In place of tank 44 having level control the feeding may alsobe carried out by the water main, a pressure-reducing valve adjustingthe pressure to the pressure at the mixing values 38,40, which isdependent on the height of mounting of tanks 26,28.

What is claimed is:
 1. A device for supplying a plurality of sprayunits, each for a die casting machine, with a fluid containing water andadditives for cooling, cleansing and/or lubricating, comprising:at leastone first central tank for storing water containing additives, theconcentration of the additives being the maximum necessary for thecasting materials, molds, and methods utilized in conjunction with thedie casting machine; a further central tank for storing water; a mixingvalve for each spray unit having a first inlet connected to said atleast one first central tank and a second inlet connected to saidfurther central tank, an outlet, and means for adjusting the proportionof liquid from said at least one first central tank and said furthercentral tank delivered through said outlet; and a pump for each sprayunit having an inlet connected to the outlet of a respective mixingvalve, and an outlet connected to the respective spray unit.
 2. Thedevice of claim 1, wherein a plurality of first central tanks isprovided, the number of first central tanks corresponding to the typesof materials to be processed in the die casting machines, and whereineach said first central tank is connected to a reversing valve having anoutlet connected to said mixing valves, said reversing valve includingmeans to selectively connect said mixing valves to one said firstcentral tank.
 3. The device according to claim 1, wherein each saidmixing valve comprises a casing (72) having a cylindrical body (76)rotatably mounted therein, said body having a hollow central portion(82) and a radial slot in its surface over a circumferential portionthereof, said slot communicating with the hollow central portion, saidcasing having a first inlet opening communicating with said first inletvia a first check valve, and a second inlet opening communication withsaid second inlet via a second check valve, said slot being adjustablypositionable opposite said first and second inlet openings, and saidhollow central portion being in communication at one end to said pumpoutlet.
 4. The device according to claim 1 or 2, wherein the centraltanks (26,28,44) are arranged at a higher level than the die castingmachines (10,12).
 5. The device according to claim 4, wherein thecentral tanks (26,28,44) ar arranged at the same level .
 6. The deviceaccording to claim 1, wherein the pumps (46,48) are formed as plungerpumps cylinders (112) .
 7. The device according to claim 6, wherein eachplunger pump includes a plunger (114) having two spaced disks (116,118),one of which faces a first cylinder volume (110) connected to the pumpinlet and outlet, and defined to receive the fluid being pumped, and theother of which faces a second cylinder volume (122) defined to receive apressurized gas, an interspace (130) between said two disks (116,118)being connected to the atmosphere via a check valve (128) for relief ofthe excess pressure.
 8. The device according to claim 7, wherein thesecond cylinder volume (122) is connected through a reversing valve(142,144) with a source of compressed gas (126) provided for the pumps.9. The device according to claim 7, wherein a check valve (136,138,140)is arranged between the pump outlet and the first cylinder volume (110).10. The device according to claim 2, wherein said cylindrical body (76)has a section (80) projecting from casing (72), a lever (98) beingaffixed to said section.
 11. The device according to claim 10, wherein amotor (106) is connected with said section (80) projecting from saidcasing (72).
 12. The device according to claim 10, wherein the section(80) projecting from said casing (72) is connected with an anglepotentiometer.
 13. The device according to claim 6, wherein the cylinder(112) of the each pump (46,48) comprises two disks (62,64) and acylindrical jacket (60) arranged between the disks (62,64).
 14. Thedevice according to claim 1, wherein the central tanks include fluidlevel controllers.
 15. The device according to claim 7, wherein saidsecond cylinder volume (112)has in a communication therewith a valve(142,144) for ventilation to the atmosphere.
 16. The device according toclaim 12, wherein the cylinder (112) includes a movable plunger (114)and adjustable stops (146) which control the length of movement of theplunger.